US3798136A - Method for completely filling small diameter through-holes with large length to diameter ratio - Google Patents

Method for completely filling small diameter through-holes with large length to diameter ratio Download PDF

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US3798136A
US3798136A US00261459A US3798136DA US3798136A US 3798136 A US3798136 A US 3798136A US 00261459 A US00261459 A US 00261459A US 3798136D A US3798136D A US 3798136DA US 3798136 A US3798136 A US 3798136A
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holes
hole
plating
substrate
taper
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J Olsen
L Romankiw
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International Business Machines Corp
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International Business Machines Corp
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
    • H05K3/42—Plated through-holes or plated via connections
    • H05K3/423—Plated through-holes or plated via connections characterised by electroplating method
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • C25D7/04—Tubes; Rings; Hollow bodies
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/03—Use of materials for the substrate
    • H05K1/0306—Inorganic insulating substrates, e.g. ceramic, glass
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/15—Position of the PCB during processing
    • H05K2203/1518—Vertically held PCB

Definitions

  • FIG.4 PRIOR ART FIG.4
  • a method and apparatus for plating through large length to diameter ratio holes in a substrate is disclosed.
  • the method consists of forming holes in a substrate which are tapered either by electron beam, or laser drilling, or by forcing an appropriate etchant through a previously drilled hole.
  • the substrates may be of any material and can be either insulating or conductive. In the instance of the former, the substrate should be of such a character that it is amenable to electroless plating or other surface metallizing techniques.
  • the interiors of the tapered holes are electroplated while simultaneously subjecting the tapered portion to agitation by forced convection.
  • a prior art plating solution of high throwing power, and forcing it through the tapered holes from the large end toward the small end causes relatively high deposition rates at the widest portion of the taper which gradually decrease along the length of the taper until the narrow portion is reached where the minimum deposition rate occurs. Under such circumstances, plating occurs non-uniformly along the length of the taper such that the tapered holes are substantially closed without leaving large, unwanted voids which contribute to poor conductivity characteristics.
  • the length of holes which may be filled can be doubled by providing a taper which decreases toward the midpoint of a substrate and from there increases in size until the opposite side of the substrate is reached. Using the same electroplating solution of high throwing power, plating through holes of this character can be accomplished while periodically reversing the direction of flow through the double taper holes.
  • Apparatus for carrying out the above described method consists of an enclosed chamber having inlet and outlet ports through which plating solution under pressure can be forced.
  • Anodes consisting of wire mesh are disposed adjacent to both the inlet and outlet ports while an element containing holes which are to be plated-through forms the cathode and is disposed intermediate the anodes.
  • electroplating solution is forced in one direction but, Where a double taper is utilized, the flow of electroplating solution is periodically reversed.
  • the method and apparatus of the present invention provides completely plated through-holes which have a length to diameter ratio in excess of 25 and, in addition, have extremely good conductivity characteristics.
  • This invention relates generally to methods for electroplating through-holes in conductive or non-conductive substrates. More specifically, it relates to a method for electroplating through-holes having large length-todiameter ratios.
  • the through-holes resulting from the method are substantially completely filled with conductive material while substrate surface portions outside the hole are covered with a much thinner plated layer than that obtained within the through-holes.
  • the results obtained are made possible by tapering the through-holes and by 3,798,136 Patented Mar. 19, 1974 the forced convection of plating solution through the holes to be plated and are much superior to those obtained using prior art techniques.
  • the degree of filling of the holes with a metal deposit depends on the relative current density inside the hole to that on the surface of the board.
  • the uniformity of plating inside the hole along the length thereof depends on the uniformity of current distribution along the length.
  • the rate of plating depends on the thickness of the diffusion layer at the deposition site.
  • the dilfusion layer inside the hole is nearly equal to the length of the holes to be plated, while outside the hole it is thinner due to convection currents set up due to plating. As a result, plating occurs mostly on the surface of the substrate and at the entrance of the holes to be plated.
  • the purpose of plating through-holes is to provide a good electrical connection between two sides of a substrate, it is desirable to have a thick metal deposit inside the holes and to keep the area of the holes small in comparison to the area of the board. Yet, from the point of view of ease of etching the conductors connecting the holes, it is preferable to have a thinner deposit on the surface of the substrate. It is desired, then, to plate at least as thick a deposit inside the hole as on the outer surface of the substrate.
  • the ratio of the deposit thickness inside the holes to that outside the holes can only approximate a value of one, and can never exceed this value except in the instance of aforementioned IBM Publication.
  • the ratio of the hole length (L) to the hole diameter (d) becomes large i.e. L-:-d 5
  • the profile of the ratio of the deposit thickness on the surface of the substrate to the deposit thickness inside the hole gradually decreases from approximately 1 at the entrance of the hole to some small value, approximately 0.5 at the center of the hole, and then increases again toward the other end of the hole.
  • the degree of filling of the holes with metal deposits depends on the relative current density inside the hole to that on the surface of the board.
  • Most prior art through-hole plating processes are concentration polarization (diffusion) controlled.
  • the rate of plating depends on the thickness of the diffusion layer at the deposition site and therefore on the rate of supply of the metal ions to be discharged.
  • All of the prior art techniques have as their object the modification of the primary current distribution which are controlled either by (a) bath throwing power, (b) additives, (c) agitation in the plating tank on the board surface and not inside the holes, and (d) on the hole length-to-diameter ratio.
  • the step of plating in at least an electroplating solution includes the step of subjecting the substrate to electroless plating to thermal decomposition of an organometallic complex, or other surface metallizing techniques, where the character of the substrate is insulating.
  • the step of forming at least a single hole in the substra e inclu es the s p of formin at least a single hole in the substrate having at least an additional tapered portion connected to the first mentioned tapered portion.
  • the tapered portions are subjected to plating in a plating solution by forced convection in a direction which is intermittently reversed. In this manner, holes having a length approximately twice the length of a single tapered hole can be completely filled with plated material of good conductivity.
  • an object of the present invention to provide a method for plating through-holes of large length-to-diameter ratio by forced convection of an electroplating solution through tapered holes.
  • Another object is to provide a method of plating large length-to-diameter ratio through-holes while simultaneously depositing metal of smaller thickness on the surface of the substrate containing the holes.
  • Another object is to provide a method of plating large length-to-diameter ratio through-holes which is simple and amenable to mass production techniques.
  • Still another object is to provide a method for forming through-holes for both conductive and insulating substrates which provides through-holes of a length approximately twice that of a single tapered hole. This is accomplished by providing a double taper.
  • FIG. 1 is a cross-sectional view of a substrate containing a through-hole which is immersed in an electroplating solution.
  • the drawing shows the lines of primary current distribution, the diffusion layer thickness, 6, and the thickness of deposited metal at various points :1, t2 on the substrate, both within and without the hole.
  • the drawing represents a prior art approach to plating through-holes.
  • FIG. 2 is a cross-sectional view of a substrate containing a through-hole immersed an electroplating solution.
  • the drawing of the prior art technique shows the primary current distribution which results from external agitation of the electroplating solution. Under such circumstances the primary current distribution covers the surface of the substrates but extends further into the hole than in the instance of FIG. 1.
  • the diifusion layer thickness 6 which has been reduced as a result of the external agitation is shown and, the resulting metallization of various thicknesses, t1, t2, at a number of points within and without the hole is also shown.
  • FIG. 3 shows a substrate containing a hole to be plated into which the primary current distribution extends to a much greater depth than that shown in either FIG. 1 or FIG. 2.
  • the extension of the primary current distribution in this manner results from ultrasonic agitation of the electroplating solution and represents a prior art approach to plating through-holes.
  • the diffusion layer thickness 6 and thicknesses of deposited metal, t1, t2, both within and without the hole, are also shown.
  • FIG. 4 is a cross-sectional view of a substrate containing a through-hole which is to be plated immersed in plating solution which is agitated by forced flow through the hole.
  • the primary current distribution extends rather deeply into the hole having been diverted by forced convection.
  • the diffusion depth 6 and the thicknesses, t1, t2, of metal deposited at various points within and without the hole are also shown.
  • FIG. 5 is a cross-sectional view of a substrate containing a tapered through-hole which is to be plated immersed in a plating solution which is agitated by forced flow through the hole.
  • the primary current distribution extends deeply into the hole, having been diverted therein by forced convection.
  • the diffusion depth, 5, is very small and the ratio of the thickness, t2, of plating within the hole to the thickness, 11, of plating on the surface of the substrate is much greater than 1.
  • FIG. 6 is a cross-sectional view of a substrate containing a through-hole which has a double taper. Also shown are the primary current distributions under conditions of reversible flow of electroplating solution. The current distributions, the thicknesses, t1, t2, of plated material and the thicknesses 5 of the diffusion layer are the same as obtained in FIG. 5 where only a single taper is utilized, except the through-hole is twice as long.
  • FIG. 7 is a partial cross-sectional, partial schematic diagram of apparatus utilized in plating through-holes which have either a single or double taper.
  • the substrate containing the through-holes acts as a cathode in the plating arrangement.
  • FIG. 8 is a perspective view of a substrate containing holes to be plated and a conductive contact element which carries current from an external source to the substrate.
  • the substrate is metallic or is rendered conductive by electrolessly plating or is metallized by other methods when the substrate is initially insulating in character.
  • Substrate 1 which is conductive because substrate 1 is either totally conductive or the surfaces of an insulating material and the holes therein have been rendered conductive by a previous electroless plating or other metallizing steps which are well known to those skilled in the plating arts.
  • Substrate 1 contains a plurality of through-holes one of which is shown in FIG. 1 and is represented by the reference numeral 2.
  • a metal layer 3 having a thickness 11 on the surface of substrate 1 extends partially into throughhole 2 and, is shown therein decreasing to thickness t2.
  • Substrate 1 acts as a cathode for an electroplating arrangement (not shown) and is immersed in an electroplating solution 4 which may be any one of a number of wellknown electroplating solutions.
  • solution 4 completely surrounds substrate 1 both inside and outside hole 2.
  • the ditfusion layer shown by the dashed lines in FIG. 1 and having a thickness, 5, is a region which is defined as the region m which the concentration of the depositing metal ion drops from that of the concentration of the bulk of the solution C to some much lower concentration at the surface G where C C and may be equal to zero.
  • Lines of primary current distribution 5 indicates the approximate relative current density distribution in the region of hole 2 and at the surface of substrate 1.
  • FIG. 2 an arrangement similar to FIG. 1 is shown except that electroplating solution 4 is agitated externally of hole 2 causing diffusion and current penetration which is quite shallow even though it represents an improvement over the technique discussed in connection with FIG. -1.
  • ex-plating solution 4 is agitated externally of hole 2 causing diffusion and current penetration which is quite shallow even though it represents an improvement over the technique discussed in connection with FIG. -1.
  • ex-plating solution 4 is agitated externally of hole 2 causing diffusion and current penetration which is quite shallow even though it represents an improvement over the technique discussed in connection with FIG. -1.
  • ternal agitation of the plating solution reduces the thickness 6 of diffusion layer 6 so that it is much smaller than in the instance of FIG. 1.
  • the approach of FIG. 2 like the approach of FIG. 1, provides a relatively high current density at the entrance to the hole and results in rapid sealing up of the hole with little or no plating on the inside wall.
  • FIG. 2 it can be seen that the external agitation, while it results in rapid sealing of the hole with little plating within the hole, represents a decided improvement over the technique of FIG. 1.
  • FIG. 3 this figure is similar to that shown in FIGS. 1 and 2 except that the current distribution 5 extends to a much greater depth than that shown in either of the previous figures.
  • the extension of the current 5 to a greater depth within hole 2 results from the ultrasonic agitation of electroplating solution 4.
  • the thickness 6 of diffusion layer 6 is even smaller than in the previous two figures and that plating is obtained within hole 2 to a greater degree than previously even though a build up of electroplated material occurs at the entrance of hole 2 due to the high current density at the entrance of hole 2.
  • the thickness 11 of metal layer 3 on the surface of substrate 1 is of approximately the same thickness as the deposit at the entrance of hole 2 but that it is somewhat larger than the thickness t2 of metal layer 3 deep within hole 2.
  • the results obtained are those which provide only satisfactory and in many cases only marginally acceptable large L/d ratio through-holes. This results from the rapid closing of the hole by a buildup of layer 3 at the entrance of hole 3 which, in turn, causes depletion of plating material from solution 4 which is disposed internally of hole 2.
  • dashed line 6 which shows the depletion layer, is positioned to show a region where the bulk concentration begins to change to lower concentrations as a result of the discharge of ions onto the surface of substrate '1 at the outset of the electroplating step.
  • the diffusion layer thickness, 6, remains substantially the same during plating and is spaced a distance equal to the thickness, 6, from the surface of plated layer 3 even as layer 3 increases in thickness during the plating step.
  • the thickness, 6, of the diffusion region is quite large.
  • the thickness, 6, of diffusion layer 6 becomes smaller.
  • ultrasonic agitation as shown in FIG. 3 is provided the thickness, 5, of depletion layer 6 becomes still smaller.
  • FIG. 4 which is a cross-sectional view of a substrate similar to that shown in the previous figures and which contains a through-hole 2 provides a solution to the problem of having thinner deposited metal layers outside the hole than within the hole while at the same time substantially completely filling hole 2.
  • electroplating solution 4 is forced through hole 2 to provide agitation deeply within through-hole 2.
  • the electrical current extends deeply into hole 2 having been diverted therein by the forced convection of electroplating solution 4.
  • the thickness, 5, of diffusion layer 6 outside of hole 2 is substantially thicker than the thickness, 6, of diffusion layer *6 inside hole 2.
  • FIG. 5 there is shown therein a cross-sectional view of a substrate 1 containing a tapered through-hole 2 which is to be plated immersed in a plating solution 4 which is agitated by forced flow through hole 2.
  • the current extends deeply into hole 2, having been diverted therein by the forced convection.
  • the thickness, 5, of diffusion layer 6, in FIG. 5, varies from a relatively large value at the surface of substrate 1 outside of hole 2 to a final thickness which is very small deeply within tapered hole 2.
  • the mechanics of plating a tapered hole are based on the fact that the gradually decreasing taper causes higher and higher velocities as the plating solution 4 is forced through tapered hole 2. As the velocity increases, the agitation of solution 4 also increases and the thickness 6 of diffusion layer 6 is decreased. In connection with the latter, it might appear that with a diffusion layer 6 of decreasing thickness 6, that one would obtain a higher plating rate where diffusion layer 6 is smallest. However, this is not the case. In the first place, the current available deeply within the hole is less than at a point near the entrance to hole 2. Since the amount of material plated out of solution is a function of current, it follows that less plating will occur where there is less current.
  • plating solution 4 is being depleted of plating material and the less material for plating is available the deeper the hole is penetrated by plating solution 4.
  • the level of bulk concentration keeps decreasing as solution 4 penetrates into hole 2 and this, by itself, contributes to the decreasing thickness, 6, of difiusion layer 6.
  • plating solution 4 encounters only a channel 7 which has the same diameter (which is changing from instant to instant) at any given instant.
  • Channel 7 can then decrease in size until only the hydraulic resistance of the channel prevents the further flow through of plating solution 4.
  • tapered hole 2 is almost completely filled with plating material 3 with the exception of a small diameter hole of hair-like dimensions down through the center of hole 2. From the point of view of conductivity characteristics, the effect of this hair-like channel 7 in the finished product is negligible. Test results have shown that plating solution contained within channel 7 after plating stops can be easily removed by blowing channel 7 clear with compressed air and rinsing with water, alcohol, acetone, or Freon.
  • FIG. 6 there is shown therein a substrate 1 containing a through-hole 2 of approximately twice the length shown in FIG. 5.
  • FIG. 6 is merely a pair of tapered holes 2 which are in effect connected together, each of which is identical in every respect with the tapered hole shown in FIG. 5.
  • hole 2 has what may be characterized as a double taper.
  • the flow of electroplating solution 4 is periodically or intermittently reversed as indicated by the double headed arrows during the plating operation.
  • solution 4 flowing from left to right in FIG. 6 provides a build-up of layer 3 on the left most tapered portion of hole 2.
  • Electroplating apparatus 10 consists of mating sections 11 and 12 from which identical portions have been removed such that, when mated, a chamber 13 is formed. Input-output ports 14, 15 connect chamber 13 to reservoirs of electroplating solution (not shown). Anodes 16 in the form of metallic screens are disposed within chamber 13 and extend across the openings to input-output ports 14, 15 and in the flow path of electroplating solution.
  • a cathode 17 which is a substrate containing holes to be plated, is disposed intermediate anodes 16 and in the flow of electroplating solution.
  • Cathode 17, as indicated previously, may be conductive or may be of insulating material which has been electrolessly plated to render its surface portion and the interior of the holes to be plated conductive.
  • Cathode 17 is connected to the negative side of a battery 18 via an ammeter 19, while anodes 16 are connected to the positive side of battery 18.
  • a conductive electrode 20 which is shown in perspective in FIG. 8 butts up against the periphery of cathode 17 to provide via a tab 21 a current path to battery 18.
  • Gaskets 22, 23 are provided where sections 11, 12 mate to prevent the escape of electroplating solution from chamber 13.
  • Anodes 16 may be made of copper or platinum mesh while electrode 20 may also be made of copper.
  • the make-up of anodes 16, gaskets 22, 23 and cathode 17 depends on what metal is to be plated.
  • electroplating solution is continuously pumped through the plating apparatus and, where cathode 17 contains holes having a double taper, the direction of the plating solution fiow is reversed periodically.
  • a typical substrate may consist of alumina or sapphire having dimensions as shown in the following Table I:
  • Hole diameter 1.0 mil. Hole length 10 to 11 mils. Hole spacing 2 mil centers. 100% of holes to have electrical resistance. 30 milliohms per hole. Width of etched interconnection wires 1 mil. Thickness of etched interconnection wires 0.5 mil.
  • the holes are made by electron beam or laser machining and are provided with a taper of approximately 1 to 15.
  • the alumina has better than a 1.0 RMS finish. Based on the resistivity of pure annealed copper, one
  • mil holes should give 18.5 milliohms resistance. This means that if only about 30% of the cross-sectional area of a one mil hole were filled with copper, this specification would be met. However, since electroplated copper, at best, can have only to of the conductivity of pure annealed copper and, since in approximately 1000 holes per wafer, one could expect some statistical distribution about the mean, it became apparent that to meet the requirement of of the holes having a resistance of 30 milliohms, it would be necessary to plate until the holes were nearly completely filled with copper. This criterion as indicated hereinabove in connection with FIGS. 5 and 6 is met by following the teaching of the present invention.
  • the wafer After electron beam machining, the wafer is cleaned with hot phosphoric acid to remove electron machining burrs. The wafer is then sensitized and activated with SnCl and PdCl respectively. When necessary, a commercially available wetting agent is used in the SnCland PdCl solution to improve wetting.
  • the wafer After the last immersion in PdCl the wafer is not rinsed but is dried by a jet of air and is then plated for approximately fifteen to twenty minutes in a commercially available electroless copper plating bath. Electroless plating is carried out in the presence of agitation, by moving the wafer back and forth to promote an exchange of the plating solution inside the holes and to facilitate the removal of hydrogen bubbles. Following the electroless metallizing step and post-baking to improve adhesion, the wafer is electroplated in the apparatus of FIG. 7 under the conditions specified in the following Table II:
  • the current density distribution were the same inside the holes as over the wafer surface, based on the number of coulombs, it would take approximately 80 minutes to fill the 1 mil diameter holes with copper. It takes only approximately ten to fifteen minutes, however, to substantially fill the holes with copper. Therefore, unlike the commonly used through-hole plating process where the ratio of deposit thickness outside the hole to that inside the hole can never be smaller than 1.0, in the present flow through plating process, the ratio can be smaller than 1.0 and can even be as small as 0.1.
  • the resulting plated holes using the technique of the present application, have an average resistance three to five times smaller than permissible; more than meeting the criterion of 30 milliohms resistance.
  • tapered holes By obtaining tapered holes by electron beam machining alone, it is possible to obtain tapered holes by machining holes of minimum diameter with an electron or laser beam. Subsequently the wafer is placed in an apparatus similar to that shown in FIG. 7 except that anodes and electrical connections are not used and, an etchant for alumina or sapphire is flowed through the holes.
  • a typical etchant for alumina is phosphoric acid.
  • the taper results from the fact that as the etchant flows into the hole, it becomes depleted of etching material as it flows through the hole and, as such, a higher etching rate is obtained near the entrance to the hole than deeply within the hole. In this manner, a
  • tapered hole of desired dimensions can be provided which avoids the diificulties inherent in electron or laser beam machining of tapered holes.
  • electroplating solutions it should be appreciated that any standard electroplating solution of high throwing power may be utilized.
  • the temperature at which plating occurs may be room temperature or higher. As a general criterion, the temperature at which deposition is carried out from a fluid carrying at least the metal to be plated should not be so high as to permit diffusion of the metal into the substrate during the time it takes to substantially completely fill the tapered hole.
  • a method for filling small diameter through-holes in a substrate substantially completely, said holes having a large length-to-diameter ratio comprising the steps of:
  • a method according to claim 2 wherein said fluid is an electroplating solution.
  • step of forming includes the step of machining a tapered hole in said substrate by one of laser beam and electron beam machining.
  • a method according to claim 2 wherein the step of forming includes the steps of:
  • a method according to claim 6 further including the step of:
  • a method for electroplating small diameter through-holes with large length-to-diameter ratios comprising the steps of:
  • a method according to claim 10 wherein the step of forming includes the step of electron beam machining a tapered hole in said substrate.
  • a method according to claim 10 wherein the step of forming includes the steps of:
  • a method according to claim 10 further including the step of:
  • a method for filling small diameter through-holes in a substrate substantially completely with a metal, said holes having a large length-to-diameter ratio comprising the steps of:
  • a method according to claim 16 further includingthe step of:
  • a method for electroplating small diameter through-holes with large length-to-diameter ratios comprising the steps of:
  • a method according to claim 21 wherein the step of forming includes the step of machining a double taper in said substrate.
  • a method according to claim 21 wherein the step of forming includes the steps of:
  • a method according to claim 21 further including the step of:

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US4496437A (en) * 1983-06-22 1985-01-29 The Dow Chemical Company Method for producing a dual porosity body
US4499655A (en) * 1981-03-18 1985-02-19 General Electric Company Method for making alignment-enhancing feed-through conductors for stackable silicon-on-sapphire
US4518465A (en) * 1983-09-17 1985-05-21 Oki Electric Industry Co., Ltd. Method of manufacturing printed wiring boards
US4587000A (en) * 1984-11-19 1986-05-06 Pellegrino Peter P Electroplating method and apparatus for electroplating high aspect ratio thru-holes
US4595478A (en) * 1984-11-23 1986-06-17 Pellegrino Peter P Turbulent cell electroplating method and apparatus
US4647476A (en) * 1984-03-05 1987-03-03 General Electric Company Insulating glass body with electrical feedthroughs and method of preparation
US4692222A (en) * 1984-11-19 1987-09-08 Pellegrino Peter P Electroplating method and apparatus for electroplating high aspect ratio thru-holes
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US4901518A (en) * 1986-11-13 1990-02-20 Maschinenfabrik Rieter Ag Open end friction spinning device for production of a yarn or the like
US4915796A (en) * 1988-10-14 1990-04-10 Charles Denofrio Electroplating process
US5100524A (en) * 1988-02-03 1992-03-31 The General Electric Company, P.L.C. Apparatus for selectively coating part of a member
US5597412A (en) * 1995-02-15 1997-01-28 Fujitsu Limited Apparatus for forcing plating solution into via openings
US20040007611A1 (en) * 2002-07-11 2004-01-15 Farnworth Warren M. Asymmetric plating
US20080169124A1 (en) * 2007-01-12 2008-07-17 Tonglong Zhang Padless via and method for making same
US20160032476A1 (en) * 2014-07-29 2016-02-04 Min Aik Precision Industrial Co., Ltd. Electroplating equipment capable of gold-plating on a through hole of a workpiece
US10184189B2 (en) * 2016-07-18 2019-01-22 ECSI Fibrotools, Inc. Apparatus and method of contact electroplating of isolated structures
CN112850347A (zh) * 2020-12-30 2021-05-28 广东成功自动化设备有限公司 一种vcp线卷对卷上料装置
US20240049384A1 (en) * 2018-03-28 2024-02-08 Dai Nippon Printing Co., Ltd. Wiring board

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JPS51126339A (en) * 1975-04-28 1976-11-04 Mamoru Kuroiwa Method of plating inner surface of holes with emitted plating solution
JPS58123685A (ja) * 1982-01-18 1983-07-22 古河電気工業株式会社 アルミニウム端子の製造方法
GB2181743A (en) * 1985-07-16 1987-04-29 Kay Kazuo Metal plating of through holes in printed circuit boards
GB8802393D0 (en) * 1988-02-03 1988-03-02 Gen Electric Co Plc Apparatus for selectively coating part of member

Cited By (28)

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US4396467A (en) * 1980-10-27 1983-08-02 General Electric Company Periodic reverse current pulsing to form uniformly sized feed through conductors
US4368106A (en) * 1980-10-27 1983-01-11 General Electric Company Implantation of electrical feed-through conductors
US4499655A (en) * 1981-03-18 1985-02-19 General Electric Company Method for making alignment-enhancing feed-through conductors for stackable silicon-on-sapphire
US4496437A (en) * 1983-06-22 1985-01-29 The Dow Chemical Company Method for producing a dual porosity body
US4518465A (en) * 1983-09-17 1985-05-21 Oki Electric Industry Co., Ltd. Method of manufacturing printed wiring boards
US4647476A (en) * 1984-03-05 1987-03-03 General Electric Company Insulating glass body with electrical feedthroughs and method of preparation
US4692222A (en) * 1984-11-19 1987-09-08 Pellegrino Peter P Electroplating method and apparatus for electroplating high aspect ratio thru-holes
US4587000A (en) * 1984-11-19 1986-05-06 Pellegrino Peter P Electroplating method and apparatus for electroplating high aspect ratio thru-holes
US4595478A (en) * 1984-11-23 1986-06-17 Pellegrino Peter P Turbulent cell electroplating method and apparatus
US4901518A (en) * 1986-11-13 1990-02-20 Maschinenfabrik Rieter Ag Open end friction spinning device for production of a yarn or the like
US4968525A (en) * 1986-11-13 1990-11-06 Rieter Machine Works Ltd. Method for production of friction spinning means
US4877493A (en) * 1987-05-01 1989-10-31 Oki Electric Industry Co., Ltd. Dielectric block plating process
US5100524A (en) * 1988-02-03 1992-03-31 The General Electric Company, P.L.C. Apparatus for selectively coating part of a member
US4915796A (en) * 1988-10-14 1990-04-10 Charles Denofrio Electroplating process
US5597412A (en) * 1995-02-15 1997-01-28 Fujitsu Limited Apparatus for forcing plating solution into via openings
US20040007611A1 (en) * 2002-07-11 2004-01-15 Farnworth Warren M. Asymmetric plating
US6767817B2 (en) * 2002-07-11 2004-07-27 Micron Technology, Inc. Asymmetric plating
US20040238952A1 (en) * 2002-07-11 2004-12-02 Farnworth Warren M. Asymmetric plating
US20050032387A1 (en) * 2002-07-11 2005-02-10 Farnworth Warren M. Asymmetric plating
US7256115B2 (en) 2002-07-11 2007-08-14 Micron Technology, Inc. Asymmetric plating
US20150092381A1 (en) * 2007-01-12 2015-04-02 Broadcom Corporation Padless via
US20080169124A1 (en) * 2007-01-12 2008-07-17 Tonglong Zhang Padless via and method for making same
US9237651B2 (en) * 2007-01-12 2016-01-12 Broadcom Corporation Padless via
US20160032476A1 (en) * 2014-07-29 2016-02-04 Min Aik Precision Industrial Co., Ltd. Electroplating equipment capable of gold-plating on a through hole of a workpiece
US9512533B2 (en) * 2014-07-29 2016-12-06 Min Aik Precision Industrial Co., Ltd. Electroplating equipment capable of gold-plating on a through hole of a workpiece
US10184189B2 (en) * 2016-07-18 2019-01-22 ECSI Fibrotools, Inc. Apparatus and method of contact electroplating of isolated structures
US20240049384A1 (en) * 2018-03-28 2024-02-08 Dai Nippon Printing Co., Ltd. Wiring board
CN112850347A (zh) * 2020-12-30 2021-05-28 广东成功自动化设备有限公司 一种vcp线卷对卷上料装置

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GB1422466A (en) 1976-01-28
FR2195696B1 (enrdf_load_html_response) 1976-06-11
FR2195696A1 (enrdf_load_html_response) 1974-03-08
IT987431B (it) 1975-02-20
JPS4951131A (enrdf_load_html_response) 1974-05-17
DE2324653B2 (de) 1975-11-27
JPS5315455B2 (enrdf_load_html_response) 1978-05-25
DE2324653A1 (de) 1974-01-03
CA976667A (en) 1975-10-21

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